Soil nailing system

ABSTRACT

A soil nailing system includes a temporary retaining wall for an excavation sidewall. Soil nails extend outwardly into the soil sidewall and are integrated with the temporary retaining wall. The soil nails comprise an easily shearable reinforcing rod made, for example, of fiberglass so that the area containing the soil nails can be excavated after permanent walls are provided in the excavation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.10/246,106, filed Sep. 17, 2002 now U.S. Pat No. 6,796,740 the benefitof the filing date of which is hereby claimed under 35 U.S.C. § 102.

FIELD OF THE INVENTION

This invention relates to temporary retaining walls and methods formaking the same adjacent property to be excavated in the future.

BACKGROUND OF THE INVENTION

Excavations for buildings normally must be shored so that the sidewallsof the excavation do not cave in during construction of permanentload-bearing walls. One method for shoring the sidewalls of theexcavation is to use soil nailing techniques. In the past, soil nailingtechniques have utilized steel anchor rods that are inserted in holesdrilled into the sidewall of the excavation. The holes are placedseveral feet apart in both the horizontal and vertical directions. Theseholes are then filled with a cementitious material such as grout thatsurrounds the steel anchor rod. A shoring wall is then formed, forexample, by shot construction, against the side of the excavation andtied to the steel anchor rods and cementitious filler material.Normally, these shoring walls are built in four-foot to six-foot highincrements as the excavation is dug deeper. The permanent load-bearingwalls are then normally built from the bottom up on the inside of theshoring walls.

Almost always reinforcing rods and the surrounding concrete grout extendinto rights-of-way adjacent to the building construction site. It isdesirable to be able to excavate in these rights of way after theoriginal building is finished. In many instances, is desirable toexcavate these adjacent rights-of-way or property. It is difficult to doso and very hard on excavating equipment when the steel rods are left inplace. Thus, the steel rods are normally removed through the permanentload-bearing wall after it is completed. In order to do this, however, ahole must be left in the permanent wall. After the steel rods areremoved through the hole, the hole must be patched with concrete and theresulting wall fully water sealed. This process leads to significantextra expense as well as complications in assuring waterproofing of thebelow ground load-bearing walls.

SUMMARY OF THE INVENTION

The present invention comprises a soil nailing system that extends intoproperty adjacent an excavation that can later be excavated withoutencountering steel rod obstructions that can result in damage toexcavation equipment. The soil nailing system includes a temporaryretaining wall for the sidewall of the soil excavation. Soil nails areextended outwardly into the soil sidewall. The soil nails comprise aneasily shearable reinforcing rod, preferably made of fiber reinforcedpolymer, surrounded by grout or other cementitious material. This groutor cementitious material is integrally tied to the temporary retainingwall for the soil excavation. Thereafter, a permanent cementitious wallis formed inwardly of the temporary retaining wall. This constructioneliminates the need for removing the steel rods used in prior soilnailing techniques. In addition, the property adjacent the temporaryretaining wall can easily be excavated with conventional excavatingequipment without harm to the equipment or to the original retainingwall or associated permanent structure. Use of the invention leads tosignificant savings over the prior art methods that require steel rodremoval, and also reduces the easement fees that must be paid to anadjacent landowner.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation view and partial cross section of a temporaryretaining wall and soil nails constructed in accordance with the presentinvention; and

FIG. 2 is a view similar to FIG. 1 showing a permanent wall formedinwardly of the temporary retaining wall.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1, a temporary retaining wall 10 is formedagainst the sidewall 12 of a soil excavation 14. Prior to forming theretaining wall 10, bores 16 are bored outwardly into the sides of thesoil excavation. These bores are generally bored at a downward angle onthe order of 10° to 20°, preferably on the order of 15°. These bores aregenerally spaced in an array on the sidewall of the soil excavationseveral feet apart in both the vertical and horizontal directions.Retaining wall 10 is formed in vertical lifts as the soil is removedfrom the excavation 14. Generally, soil is removed in lifts ofapproximately four to six feet, depending upon the condition of thesoil. The bores 16 are then formed thereafter.

Reinforcing rods 20 are inserted into the bores 16. The distal end ofthe rods carry conventional centering devices 22 that maintain the rods20 approximately in the center of the bore. One or more of the centeringdevices 22 can be utilized to assure that the rods 20 remain in thecenter of the bores 16 throughout its length. The rods 20, in accordancewith the present invention, are composed of a material that is easilyshearable in a transverse direction, and that yet has adequate tensilestrength to provide lateral reinforcement to the temporary retainingwall 10. Preferred materials for the rods include fiberglass reinforcedpolymers, typically referred to as fiberglass.

After a rod 20 is inserted into a bore 16, cementitious material,ordinarily grout, is “tremie” placed, that is, first injected into thebottom end of bore 16, and then inwardly toward the wall of theexcavation, to completely surround the rod 20. The face of the retainingwall 10 is then formed. This can be done in any of a variety ofconventional manners, using for example, a conventional cementitiousmaterial that is poured or that can be blown onto the sidewall. Theblowable material is normally referred to as shotcrete. The cementitiousmaterials in the bore and the wall are normally allowed to curesimultaneously, thus making an integrated retaining wall with soilnails.

The rods 20 have sufficient length so they extend inwardly into theexcavation 14 sufficiently so that they also extend through theretaining wall 10. Preferably, a reinforcing plate 24 is positionedaround the rod 20 and against the inner side of the temporary retainingwall 10. The inner end of the rod 20 is preferably threaded and a largenut 26 is threaded onto the end of the rod against a washer 28, which inturn bears the reinforcing plate 24. Other suitable connectors known inthe art may also be employed. Once the cementitious materials are cured,the nut 26 is tightened until the proper tension is placed against theplate 24 and the wall 10. Thereafter, subsequent lifts of soil areremoved from the excavation and additional segments of the temporaryretaining wall are serially produced as the lifts are removed from theexcavation.

The rods preferably used in accordance with the present invention areavailable from Dywidag Systems Int'l, of Bolingbrook, Ill., under thetrade name Glass Fiber Anchors. These rods have a tensile strength onthe order of from 40000 psi to 60000 psi. These rods are alsoadvantageous because their lateral breaking strength can be designed bythe appropriate choice of manufacturing resins known in the art, so thatit actually reduces over time. Thus, the more time that passes betweentheir installation and excavation eases the task of breaking throughthem when eventually excavated.

Referring now to FIG. 2, a permanent concrete floor 40 is formed on thebottom of the soil excavation 14. A separate permanent vertical wall 42is then formed against the temporary retaining wall 10. This wall isdesigned to permanently bear the lateral loads of the excavation, andonce in place alleviates the need for the temporary shoring wall andassociated fiberglass anchor roads. The ends of the rod 20 arecompletely encased in the permanent wall 42. The present invention thuseliminates the need for the holes otherwise required for removal of theprior art steel reinforcing rods. Thus the need to patch and seal thepermanent wall 42 after rod removal is also eliminated. The presentinvention therefore provides much more permanent and trouble-freepermanent wall 42, as well as a more uniform and aesthetic interiorfinish. In addition, the soil nails comprising the fiberglass rods caneasily be excavated without damage to the excavating equipment or thepermanent load-bearing wall. By excavation it is meant any removal ofmaterial manually or by machine that would require breaking through afiberglass anchor rod and its surrounding grout.

While the preferred embodiment of the invention has been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.

1. A soil nailing system comprising: a temporary cementitious retainingwall for a soil excavation having a sidewall, said sidewall beingadjacent to adjoining property capable of excavation; soil nailsextending outwardly into said soil sidewall from said temporarycementitious retaining wall and into said adjoining property capable ofexcavation, said soil nails comprising an easily shearable reinforcingrod surrounded by cementitious filler material, said cementitious fillermaterial being affixed to said cementitious temporary retaining wallsaid soil nails being shearable upon excavation of said adjoiningproperty; and a separate, lateral, permanant load-bearing wall formedinwardly of said temporary cementitious retaining wall, said permanantload bearing wall encasing said soil nails.
 2. The system of claim 1,wherein said easily shearable rod comprises a fiber reinforced polymer.3. The system of claim 1, wherein said filler material and saidretaining wall comprise a cementitious material, the filler material andthe retaining wall being integrated by said cementitious material.
 4. Amethod for making a temporary retaining wall for a soil excavation, saidsoil excavation having a sidewall, said temporary retaining wall havingportions that extend into adjoining property capable of being excavated,said method comprising the steps of: boring holes in the sidewall ofsaid soil excavation that extend into the adjoining property capable ofbeing excavated; inserting easily shearable reinforcing rods into saidholes, said rods extending into said adjoining property said rods beingcapable of being sheared when said adjacent property is excavated;filling said holes with and forming a temporary retaining wall fromcementitious material; tying said rods to said temporary retaining wall;and forming a separate, permanent, lateral load-bearing wall inwardly ofsaid temporary retaining wall, said seperate, permanant, lateral loadbearing wall encasing said reinforcing rods.
 5. The method of claim 4,wherein said easily shearable reinforcing rod comprises a fiberreinforced polymer.